How do I get a Java maven build to fail for compiler warnings?

Question

I am trying:

        <plugin>             <groupId>org.apache.maven.plugins</groupId>             <artifactId>maven-compiler-plugin</artifactId>             <version>2.3.2</version>             <configuration>                 <source>1.6</source>                 <target>1.6</target>                 <compilerArgument>-Werror</compilerArgument>                 <fork>true</fork>             </configuration>         </plugin> 

but with no joy. Any ideas now to get medieval on such errors as suggested at this blog post?

Answer 1

Update for the year 2015, using Maven 3.3 and Java 8.

Here's a minimal compiler configuration that enables all warnings and makes the build fail whenever warnings occur.

<plugins>     <plugin>         <artifactId>maven-compiler-plugin</artifactId>         <version>3.3</version>         <configuration>             <source>1.8</source>             <target>1.8</target>             <showWarnings>true</showWarnings>             <compilerArgs>                 <arg>-Xlint:all</arg>                 <arg>-Werror</arg>             </compilerArgs>         </configuration>     </plugin> </plugins> 

Bits of note:

• <showWarnings>true</showWarnings> is required. For reasons unknown, Maven by default actively suppresses warnings with the -nowarn flag, so the -Xlint and -Werror flags would be ignored.
• showDeprecation doesn't need to be enabled because -Xlint:all already emits deprecation warnings.
• Experimentation shows that fork doesn't need to be enabled, even though the documentation says otherwise.

Answer 2

New in maven-compiler-plugin 3.6.0: the failOnWarning flag. This worked for me:

  <plugin>     <artifactId>maven-compiler-plugin</artifactId>     <version>3.6.0</version>     <executions>       <execution>         <id>compile</id>         <phase>process-sources</phase>         <goals>           <goal>compile</goal>         </goals>         <configuration>           <compilerArgument>-Xlint:-processing</compilerArgument>           <failOnWarning>true</failOnWarning>         </configuration>       </execution>     </executions>   </plugin> 

Note that I had to exclude the processing lint or otherwise auto-matter's annotations would break the build with cryptic "symbol not found" errors.